Silly question time, but I had the little single-cylinder 4-stroke B+S
engine from our mower in bits the other day (so it was stationary at the
time ;) and it has a mechanical governor mechanism linked to the crank.
Question is, how come it needs the governor at all - i.e. how come just
altering the throttle position from the control panel isn't enough to
regulate engine speed?
Is it something to do with the small size of the engine, the nature
of it being a single cylinder, or some other reason? (I just got to
thinking that car IC engines don't have such a system - so what makes it
necessary on the mower?)
You play the part of the governor on the car, with the car's own ECU taking care
of idling etc.
The lawn mower engine has the governor there so that it can cope with changing
loads etc and still keep within a reasonably level speed range.
Peter A Forbes
Prepair Ltd, Rushden, UK
On Fri, 14 Aug 2009 16:19:55 +0100, Peter A Forbes wrote:
Thanks - that makes sense. Also suggests that I might want to take a
look at the mechanism, then, as the mower has a habit of wanting to stall
when cutting thick stuff on uphill stretches - playing with the throttle a
little before such a section (just as I would in any regular
vehicle) always works, but it sounds from what you say like the linkage
between governor and carb might not be adjusted quite right...
On Fri, 14 Aug 2009 16:19:55 +0100, Peter A Forbes wrote:
Aye the "throttle" on a lawn mower is an engine speed set control.
It's more akin to cruise control in a car. You set a speed and some
other control system adjusts the fuel as required to maintain that
There are lawnmowers which don't have a centrifugal governor, but I'm
not sure that they're commonly made today. If you don't have a governor,
you need a well-positioned throttle lever which isn't too stiff. Many
modern lawnmowers have an awful throttle lever which you just want to
On Mon, 17 Aug 2009 22:36:20 +0000, Christopher Tidy wrote:
Hey - *the* Chris Tidy? :-)
Yeah, the throttle's not too stiff on ours, but I think that's more down
to years of wear than anything!
The other thing that struck me as odd is that the governor sits in an oil
bath in the engine sump - but only partially submerged. I'm surprised that
both oil level and oil temperature (i.e. thickness) don't mess somewhat
with its operation.
Externally there's quite the linkage between the governor 'output' and the
carb and throttle cable, so I need to check that for fouling (and against
the original parts diagrams, as I wouldn't be surprised if someone hasn't
had it in bits before) - maybe I can sort out some of the stalling / speed
Indeed. How are you doing? Are you still doing data recovery in
Cambridge? I was working in factory control systems for a while, but am
now working on a business idea.
Never seen one like that before. It might be a small engine thing done
to save space, like the gearbox in the sump of the original Mini. I'm
surprised it doesn't cause the oil to foam.
I don't usually tinker with the smaller lawnmower engines. This is my
Once you've reassembled the governor, just be ready to pull off the
spark lead when you first start the engine. I once rebuilt one and got
two components the wrong way round, with the result that the throttle
wouldn't close at all. A bit scary!
By the way, are you still involved with the Bletchley Park museum? I
came across an odd computer base unit in our shed recently, marked "OEM
ScreenTyper". Probably only good for spares; there's no monitor or
keyboard. I suspect it's not very interesting, but it's there if anyone
On Tue, 18 Aug 2009 00:01:26 +0000, Christopher Tidy wrote:
:-) Nope, I hopped the Pond at the end of 2007 - currently living in the
wilds of MN. Got married, then bought a big old farmhouse + buildings
(a perpetual DIY project!). Life's pretty good... I just need some
interesting old 'junk' to tinker with and to fill the space!
Well it's got an oil slinger built in, so it acts as a crude sort of oil
pump too - I'm just surprised that the governor can do its job properly
under those circumstances. I presume they saved money by doing it like
that, and maybe any changes in behaviour due to oil level / temp were
Well it's not that small I suppose - it's around 350cc and rated at 10HP,
although it's a little under-powered for my tastes (38" cut on the
mower's deck, and takes me between 2 and 3 hours to cut the lawns)
Nice! When it flashed up '1947 Dennis' I thought you'd gone and bought a
vintage fire engine ;)
My current 'toy' is a '67 Ford pickup, but I'm keeping a serious eye out
for a little old stationary engine of some kind (or even a big one - the
concrete floor in the barn seems pretty heavy-duty)
Heh, indeed. The latest drama with this one was the starter solenoid
sticking in the 'on' position so that the starter wouldn't turn off;
giving it a good thump did no good and all the wires are bolted
terminals - by the time I'd got back with a spanner there was smoke
pouring from the starter...
Yes, I am - I'll do some digging and/or mention it in case it's something
Congratulations. Are you at the western end of the Rust Belt or in
remote Fargo type country? Sorry, I'm thinking about that creepy Coen
brothers film :-). If you're in the Rust Belt, I imagine there's plenty
of machinery to collect. Never been to that part of the US, but I'd like
to. I've got an invite to see Tom Gardner's brush factory (Tom from
rec.crafts.metalworking) if I'm ever in Ohio, but that's the far end of
the Rust Belt. Closer to Detroit I think. I heard that Detroit's a
shadow of its former self today.
Do you mean a disc slinger, or just a stick which repeatedly dips into
I wish! Fire engines aren't that expensive actually. At least to buy. If
I ever get rich...
I love the design of American vehicles. The classic ones, anyway. Today
many are starting to look like European or Japanese cars. I could fancy
a Lincoln Town Car or Cadillac DeVille. I think they were designed with
one purpose in mind: having a bigger car than your neighbour.
Did you take the Triumph Stag with you?
I'm pretty sure it's rare. But I'm not sure if it's interesting. I found
a bit of information on a newsgroup. Not sure if it's primarily a
terminal or word processor, or if it's a proper computer. Apparently it
has a Z80 processor:
There are also two 5.25" floppy drives in the front. It used to power up
10+ years ago. I never had a keyboard, and the monitor broke. The
monitor was already cracked and fell to pieces. The monitor looked like
an early IBM monitor and had the same orange text. So I just have the
base unit now. Can't guarantee it works, but if anyone's interested, let
me know. It'll be around for a few months but eventually I need to clear
the space. They can e-mail me at chris AT ruggedmachines DOT com.
Good to hear from you again!
I've got a couple of the early Amstrad laptops. They have black/orange
screens - made me think of them! - and they are useful for writing in bright
sunlight in the garden. The operating system is a version of DOS 4 (I think)
with a cut down version of Wordstar 6. It all fits on one 3.5" floppy &
saves to another.
Trouble is that 3.5" drives are getting rare now & although I have a spare,
their days are numbered!
Wordstar 3.3 was by far the best DOS version, ran from a floppy and only 300K or
I think the Osborne Luggables we have are supplied with WS3.2 on 320K
Peter A Forbes
Prepair Ltd, Rushden, UK
First truly portable PC, Adam Osborne was part of the Osborne publishing group
family IIRC. His first portable Osborne 01 had 160K drives and a 5" orange
screen, there's a nicer 01/2 which is much improved, then he went into what we
would today call a laptop, but the rest of the industry had caught up with him
and he went bust.
We have a few of them now, 5 I think :-))
Plus a Philips P2000C luggable (3) a Compaq luggable and another which I haven't
opened since we bought it, but is truly a luggable!
Peter & Rita Forbes
On Wed, 19 Aug 2009 15:16:25 +0100, kimsiddorn wrote:
Lots of Amstrads were 3" floppy, not 3.5", and those are a real git to
find media for (and the drives themselves aren't always particularly
One thing I've found is that modern 3.5" media is usually junk and
extremely unreliable (presumably quality control went to hell
once sales started falling off) - I get much better reliability from
recycling disks from "back in the day" than buying new.
A 3.5" drive failing is very rare, though - although it's worth cleaning
the heads every once in a while with a cotton bud soaked in isopropanol.
On Wed, 19 Aug 2009 02:24:23 +0000, Christopher Tidy wrote:
Fargo end - we're about 2 hours' drive east of Fargo (I've been there
quite a lot, but not had chance to see the film yet :-) The population
density's some stupidly low number where I am (and basically no building
regs other than "no putting a new house on anything less than 6 acres",
which is nice)
Yeah, bit too far north here - although there's lots of logging heritage
(and so chance of finding some interesting stuff related to sawmill
machinery). As mentioned in one of the tractor threads though there's a
*lot* of old 1940s/1950s row-crop tractors just laying around abandoned in
fields, so I'll see what I can do there.
Yeah, I hear that too (and US cars are next to useless - not only are they
backward mechanically, but the modern ones lack any of the style / grace
/ detail of the older metal)
It's a disc-type slinger, with a couple of little vanes on it.
:-) They cost a fortune here, but then US folk are extremely nostalgic
about the fire service, so I suppose that pushes the price up.
My current plan is to get a basket-case '40s 1 or 1-1/2 ton truck and
build a wooden camper body onto the back, but that's waiting until the
finances are in better shape (which is a shame, as I saw the perfect one
for sale a few weeks ago)
Heh, the first car my wife had when she got her driving licence (at 16 or
17, can never remember which it is here) was a sodding great Cadillac. I'm
a real sucker for the 50's and earlier stuff (I found the remains of a '39
Packard on our land, but it's just too far gone to do anything useful with)
Probably. I don't think car marketing has changed much - I mean given the
enormous value drop post-purchase there's little incentive to own a new
vehicle other than to show off to the neighbours.
Sadly, no - it had a lot of bodywork needed doing and I just didn't have
the time to sort it out, so with much regret I sold it before I left. I'd
love to find one this side of the Pond (in original condition - lots of
the ones here ended up with people swapping the engine out for Chevy stuff)
It sounds like it might be some sort of generic CP/M box - although I'm
not sure if the "screentyper" bit implies some sort of interesting
functionality. Maybe it just had a light-pen or something.
I looked up Fargo and it looks different from the impression I got from
the film. From the film I'd expect an icy, remote town with about 10,000
inhabitants. But in reality it looks bigger and more lively. I'd
recommend the film but it's not for the squeamish. It's pretty sick in
I wonder if part of the purpose of the disc is to keep the oil away from
the governor? Or it could be an air vane governor, but that sounds very
unlikely given that it's inside the crankcase. Briggs & Stratton did
make a gold-painted 3 hp engine in the '60s or '70s which had an air
vane governor (and possibly other models), but that system used the
flywheel fan as a source of air. It was crude. I don't think it did much
more than limit the engine's top speed when unloaded.
Some disc lubrication systems also have a small chamber in a high
location, in which the oil collects and flows down to the bearings under
I remember watching a documentary about American fraternity life. One
fraternity (at Iowa State I believe) had an immaculate '50s fire engine
with open-air bench seats on the back. They used it as their transport
for weekend drinking trips.
In Boston I spent an evening with a few guys in a fraternity. Some of
them had stolen a complete cast iron fire hydrant which had become a
living room ornament. The thing must have weighed at least a couple of
hundred pounds and it was at the top of a winding staircase on the third
If there's an engine still in the car, that might be salvageable. I've
seen complete rust buckets where the engine looked fine internally.
I think a CP/M box is likely. I got it with a bunch of very boring boxes
which I think ran CP/M. They had no disks and seemingly very little
functionality without a network connection. I kept this one because it
looked more interesting, but never got it run properly. If there was a
light-pen I never had it.
On Thu, 20 Aug 2009 02:49:25 +0000, Christopher Tidy wrote:
I think they cheated, and the film was actually shot over the border in
Canada as it was cheaper to do it that way! I think there's about 100,000
folk in Fargo so it's a reasonably big place. Certainly icy, though -
Winter up here generally lasts for 5 months with temperatures down to -30
(but we don't get much Spring or Autumn, and Summers are probably warmer
and more sunny than the UK). There was continuous snow cover here from
the end of last October to some time in May.
No, governor's weighted and sits well into the oil; seems like a weird way
of doing it but I suppose they had their reasons. Heck, I suppose
maybe it's clever, and actually lowers/limits peak RPM until the engine's
warm (i.e. until the oil's thinned)
I remember my dad's early-70's Flymo being like that, although I'm not
sure whose engine that was (maybe Flymo made their own?). That mower
finally died a death last year apparently, so it managed around 35 years
of service (although I'd had it apart at various times to fix faults, of
It's possible this has something like that somewhere under the flywheel;
I know there's a drain channel leading down from there into the valve
case, but I've never had cause to pull the flywheel yet and see. I'm not
sure why the valve case is so big, actually; maybe it fills with oil
during operation to keep the valve stems properly lubricated.
Heh, they're everywhere here still so you'd have no trouble finding one,
although shipping would be expensive. Too 80's and angular for my tastes
Oh, it's in pieces and was scattered around the property when we moved in.
The body / doors were sitting way out back, the wings, running boards,
seats and radiator cowl I discovered in various places within our
woodland, and the chassis rails are still sticking up out of the ground in
one spot and supporting an enormous grapevine :-)
No sign of an engine, or any of the chrome trim (other than one
doorhandle). There's a homebrew trailer rotting away in the woods though
which might have the front and rear axles on it (hard to tell, but they're
from some very old car).
All too rusty and fire-damaged in cases to be useful for much, sadly - I
actually wonder if it held some sort of sentimental value and was treated
to some kind of ceremonial destruction upon someone's passing, as it would
have taken real effort to demolish it the way it has been!
I did find some extremely heavy implement wheels, too, such as the
kind of size/style as seen on the front of traction engines - I've
no idea what they would have come from, but it must have been big
(maybe a thresher; they seem to wide and large to have been a
seed drill or whatnot).
Current plan is to use them for decoration at the end of the driveway,
although they really scream "flywheels for homebrew engine" ;-)
Network in what sense? Networking is often historically quite interesting
in CP/M crates, as in their heyday terminals/mainframes were the norm -
it's unusual to see CP/M boxes hooked up together at all, and the
technologies used can be quite bizarre.
Just looked it up. Seems it was filmed in Minnesota and North Dakota,
with the coldest scenes being filmed in North Dakota. Apparently Fargo
was used for only one shot in the film:
I imagine that once it's up to running speed the governor creates a void
in the oil and little oil touches it. It's probably something you can do
without ill effects if your governor is small and spinning fast. If it
was large and spinning slowly, I think the interference of the oil would
be more significant.
The engine I'm thinking of is a horizontal shaft engine, fitted to some
Hayter cylinder mowers. I think Briggs & Stratton have supplied engines
to Flymo at some time. It's a while since I saw a metal-deck Flymo.
The valve case might have a high inlet and a drain at a lower level, to
control the oil level. The Dennis I'm working on has an arrangement like
this. The main bearing is supplied pressurised oil from a pump. Some
trickles out into the gear case, but the outlet hole is part way up the
wall. So a pool of oil collects which is deep enough to wet the bottoms
of the gears.
I haven't actually taken the engine apart to see this (the engine looks
in good order internally, so it's staying assembled for the moment). The
manual is full of cross-sectional drawings of the engine, which are
unusual and fascinating.
Wish there were some Cadillacs here! Still, maybe it's a good thing. I
can't afford one. Neither could I afford the fuel (yours is still
I guess from the point of view of a machinery collector, you get lucky
with some things in each country. I've heard of people abroad finding it
difficult to locate a genuine Lister stationary engine, but they're
I see. Thought you meant a complete but rusty car :-).
Maybe they are actually front wheels from a large early tractor or
In the sense that they had no hard disk, no floppy disk and had a
modular Ethernet socket in the back. Also, they wouldn't do anything
much. There were a few menus you could flip through, but no useful
software. I don't remember too clearly though; this was about 13 years ago.
I can check for a hard disk and network socket in the OEM ScreenTyper if
you like. From the bunch it was the machine I kept because it looked
On Sat, 22 Aug 2009 01:57:25 +0000, Christopher Tidy wrote:
Interesting. Must be thinking of something else where it was all done in
Canada. Fargo is technically in ND - but it's twinned with Moorhead on
the MN side, and everyone tends to forget about the latter and just call
it all Fargo :-)
That could be. From memory the gearing's such that it's running at engine
speed - and that engine's designed to sit at upwards of 3000 rpm for
most of its life, so it's spinning at a fair old rate.
Ahh, OK - the one in my dad's mower was a vertical. Plastic deck; one of
the plastic struts connecting the deck to the engine broke years ago, and
I have a feeling that another one of them failing was a contributing
factor to him retiring the thing (that and the engine was getting due
for another tear down and rebuild, and I wasn't able to come and do it!)
After some googling, I think he must have got it in the late 70s, so not
quite as old as I thought (apparently Flymo didn't settle on the orange
colour until 1977)
That sounds like it might be the case - I think I do remember a drain at
the bottom of the valve chamber. The engine breather / filter is in the
cover for the valve case, which might also explain its size.
One interesting thing is that I'm sure the manual said that the engine
could run in any orientation (it's run as a vertical shaft right now),
swhich surprised me; I would have expected them to be designed as
horizontal or vertical, but not capable of doing both.
I can't resist taking everything to bits. 99% of the time I put it back
together again afterwards :-)
It's at what, $2.52 / gallon here right now. But that's a US gallon, which
is smaller than the UK gallon, and it's not quite as potent as UK fuel (I
the the norm is about 95 RON in the UK, isn't it? The US standard stuff
works out to about 91 or 92)
I think it's still about 1/8th the price of UK petrol - but then the
distances here are sodding huge, people here think that a vehicle that can
attain 30mpg is good - plus of course average salaries here are lower. In
'real terms' (i.e. percentage of salary going on fuel) I suspect it works
out as somewhere around 1/3 of the UK. Still not to be sniffed at!
Yeah, apples and oranges I guess. I can't get any vintage computers around
here, but it's quite cheap and easy to pick up a 40 year old vehicle.
Well, right on the rusty :-) It might be complete, too - the folks who
owned the place in its farming days buried just about everything; there
just weren't the rules and regulations about disposal back then. I tripped
over a mostly-buried tractor gearbox last year. Keep meaning to buy a
(I found a little old stationary engine manual in the dirt on the garage
floor when we moved in - I may have mentioned that. Wouldn't surprise me
at all if the engine it goes with isn't out in the woods somewhere)
Not sure - they were on the remains of a wooden axle when I found them,
but I couldn't tell if that was original or not. They seem far too
heavy-duty for a simple cart or whatever. No treads though (metal or
rubber) which makes me think it was more likely from something that was
towed, not driven or used for steering ahead of driven wheels.
That sounds quite unusual... by modular do you mean RJ45? I've not seen
those until later in with Ethernet or Token Ring, but by then it's
surprising to see a Z80 at the heart of things. And I don't think I've
ever seen a network-connected text-only terminal (graphical X terminals
are another matter) - they were always RS232.
Almost sounds like a network packet monitor or something - but then the
'screentyper' name seems a bit odd. Curious!
I'm sure the English would find a way to live with 91 RON petrol if it
was as cheap as yours :-).
A fair number of traction and ploughing engines had plain front wheels
actually. Maybe they're off something like these?
Yes, but I didn't mean that the RJ45 sockets are on the same machine
that has the Z80 processor. They were on later, more boring machines.
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